I've had the Timefactor sending tempo via MIDI to my Pitchfactor for a while now, and it's always seemed a bit sketch – just like you said.  It seems like even when I tap a new tempo it will only update the other pedal if there is a significant difference of a couple BPM's.  Sometimes when the PF syncs, the display is reading 1BPM off from the TF.  I've never quite figured it out, but it's always seemed a bit off.